With the rapid development and popularization of computers, more and more attention had been paid to the development of more user-friendly human-machine interface for facilitating the applications of computers. Currently, in addition to keyboards, there are many kinds of pointing devices, such as computer mouse and trackball, being adopted as a means to communicate with computers.
Currently, there are many kinds of computer mouse available on the market, which are the most popular human-machine interface used by computers as cursor-control device. There are three basic types of mice, which are mechanical mouse, LED optical mouse and laser mouse with respect to the different means of detection. However, since the aforesaid mice are constrained to use on a surface, that is, they are only capable of detecting and defining two-dimensional movements, they can no longer meet the requirements of today's video games and multimedia applications, which desire to have a pointing device capable of producing three-dimensional output. Therefore, most manufactures are focusing there research on developing a pointing device with two-dimensional and three-dimensional detection ability.
One such research is a pointing device disclosed in U.S. Pat. No. 5,825,350, entitled “Electronic Pointing Apparatus and Method”. The foregoing pointing apparatus is capable of controlling cursor movement and selecting elements on a computer screen no matter it is being held to move on a surface or in a free space, in which two gyroscopic elements are provided for indicating yaw and pitch movements of the pointing apparatus in free space, and a mouse ball and relating mouse ball encoders are provided for indicating movement of the pointing apparatus on a surface. Although the aforesaid pointing apparatus is operable no matter it is being held to move on a surface or in a free space, it still has following shortcomings: (1) the mouse ball, being the moving part of such pointing apparatus, can become dirty or be affected by dust, damaging the sensitivity of the pointing apparatus. (2) The use of the two pricey gyroscopic elements will cause the manufacturing cost of the pointing apparatus to increase.
One another such research is a spatial input apparatus disclosed in U.S. Pat. No. 4,839,838. The aforesaid spatial input apparatus including a series of coplanar, single axis accelerometers configured to provide information on translation along and rotation around a set of orthogonal axes. However, as the angular velocity variation relating to a movement of the spatial input apparatus is detected by the series of accelerometers and determined by a differential operation that the accuracy of the detection as well as the differential operation are not quite satisfactory, the sensitivity of the spatial input apparatus is questionable.
Therefore, it is in need of a pointing device that is accurate and convenience to operate no matter it is being held to move on a surface or in a free space.